Catheter with removable cannula for puncturing a body cavity and cannula for the use with a catheter which can be moved in the cannula

ABSTRACT

The aim of the present invention is to provide a catheter with a puncturing cannula which may be removed from the catheter without risk of injury for the patient and the nursing staff nor risk of damaging the equipment, and whose tip is protected before as well as after puncturing the body cavity. According to the invention, this object is satisfied by a catheter with removable cannula ( 1 ) for puncturing a body cavity, whereas the catheter can be moved freely in the longitudinal direction in the cannula ( 1 ). The cannula is characterised in that it is tubular in shape and provided with a longitudinal slot ( 10 ) extending over 45° to 180° of the circumference of the cannula ( 1 ) and in that it is provided in a tubular sheath ( 2 ) so that they can be displaced in the longitudinal direction inside said tubular sheath ( 2 ).

The present invention concerns a catheter with a removable cannula forpuncturing body cavities as well as a cannula of such type.

Several areas of medicine regularly call for laying pathways foraccessing body cavities to remain on the patient for prolonged period.To this purpose, the body cavity must be punctured with a cannula beforeintroducing a catheter therein. This is, for example, the case forcentral vein catheters or for subpubic puncture of the bladder throughthe abdominal and vesical walls.

In most known processes, the catheter is guided in the cannula. Thepuncture of the body cavity is conducted in a first step with thecannula. The catheter is then inserted into the body cavity via thecannula before the latter is removed. The cannula is afterwards situatedon the catheter and must be removed. Since the end of the catheteropposite the patient is generally provided with means for connection toother devices, the cannula cannot be removed via that end.

Several solutions are known for removing the cannulas from catheters insuch cases. According to document DE 2 204 211, a cannula can beprovided with a rupture line of the tubular wall along which it can beseparated into two parts, then removed from the catheter. Separating thecannula nevertheless requires a lot of strength and may cause theformation of protruding edges and hence the risk of injuries. On theother hand, the catheter may be damaged.

The aim of the present invention is to provide a catheter with apuncturing cannula which may be removed from the catheter without riskof injury for the patient and the nursing staff nor risk of damaging theequipment. Another object is to provide a catheter with a puncturingcannula whose tip is normally protected or unaccessible so as to excludeany inadvertent risk of injury for the persons handling the cannula andthis, before as well as after puncturing the body cavity.

According to the invention, this double object is satisfied by acatheter with removable cannula for puncturing a body cavity, whereasthe catheter can be moved freely in the longitudinal direction in thecannula. The cannula is characterised in that it is tubular in shape andprovided with a longitudinal slot extending over 90° to 180° of thecircumference of the cannula and in that it is provided in a tubularsheath so that they can be displaced in the longitudinal directioninside said tubular sheath. Advantageously, the cannula may be securedin the sheath either in a retracted position where the tip of thecannula is protected by the end of the sheath, or in an extendedposition where the tip of the cannula protrudes beyond the end of thesheath. When the cannula/sheath assembly is fixed in the extendedposition, it is ready for puncturing a body cavity.

According to the invention, the cannula exhibits a longitudinal slotwhich extends over 45° to 180° , preferably slightly less than 180° , ofthe circumference of the cannula. In practice, it has proven appropriateto choose longitudinal slots extending over 130° to 170° and especiallyover 150° of the circumference of the cannula. A catheter adapted to theinner diameter of the cannula and inserted therein may thus be removedfrom the cannula along the longitudinal slot. The cannula is arrangedinside a tubular sheath so that it can be moved therein in a controlledmanner. It may especially be a pipe made of flexible plastic material.The inner diameter of this tubular sheath is adapted to the externaldiameter of the cannula. The catheter is then held securely in thecannula in spite of the longitudinal slot.

The object of the invention is also satisfied by a catheter with thefeatures described above which is characterized in that the tubularsheath is arranged in the cannula so that it can be moved in thelongitudinal direction inside said cannula, whereas the catheter isarranged inside the tubular sheath. The invention is described belowwith reference to the embodiment having a tubular sheath outside thecannula. However, the man of the art can obviously also arrange thetubular sheath inside the cannula.

For puncturing a body cavity, for example, the bladder, the cannula ismoved in the peripheral tubular sheath so that the tip of the cannulaprotrudes therefrom so that the puncture can take place. Once thepuncture has been done, the catheter is inserted into the body cavityvia the cannula. The catheter is thus guided securely into the cannulavia the tubular sheath.

After inserting the catheter, the cannula is first brought back into aretracted position with respect to the tubular sheath, then thecannula/tubular sheath assembly is removed. The catheter can be movedfreely in the cannula, its end stays in the body cavity whereas thecannula and the tubular sheath are removed to be located on a section ofthe catheter outside the patient's body.

According to the described embodiment, there are different methods forremoving the cannula from the catheter. The first comprises separatingthe tubular sheath from the cannula. The longitudinal slot in thecannula is then exposed. The cannula can be removed from the catheter.The tubular sheath does not present any risky element and can remain onthe catheter, especially when the tubular sheath is made of flexibleplastic material.

Optionally, the tubular sheath may be provided with a rupture line inits wall in the longitudinal direction located just above the slot ofthe cannula. The tubular sheath can be broken or split along the ruptureline and thus enable to remove the cannula/tubular sheath assembly fromthe catheter. The risk of injuries is here particularly low when thetubular sheath is made of flexible plastic.

Alternately, the sheath may also exhibit two rupture lines, parallel toone another, so that a longitudinal section can be removed from itswall. The longitudinal section can be advantageously removed from thewall of the tubular sheath while the tubular sheath is still situated onthe cannula. The longitudinal slot in the cannula is thus exposed andthe cannula can be removed from the catheter with the rest of thetubular sheath. The tip of the cannula is still protected by the tubularsheath after having been removed from the catheter which enablespreventing from any risk of injury.

If the tubular sheath is provided with two rupture lines between which alongitudinal section of the wall can be removed, the width of thissection must preferably be adapted to that of the longitudinal slot ofthe cannula. The wall section between the rupture lines is preferablyconnected to a manipulation section with which the wall section can beremoved along the rupture lines.

In an embodiment, the cannula and the tubular sheath exhibit fittingsfor connecting both pieces to each other removably. Preferably, bothpieces are snapped to each other, when the cannula and the tubularsheath are in a position in which the tip of the cannula is included inthe tubular sheath and it hence protected against injuring the nursingstaff.

The aim of the present invention is then satisfied by a cannula to beused with a catheter and having the features described above.

According to the application domain, the cannula may exhibit differentdiameters. The outer diameter of a cannula inserted into a tubularsheath is preferably smaller of the order of 0.1 mm than the innerdiameter of the sheath to be able to slide easily inside the sheath.

The invention is explained more accurately below using the appendedfigures:

FIGS. 1 a to 1 c illustrate a first embodiment of the cannula accordingto the invention in a perspective view;

FIGS. 2 a to 2 d illustrate a second embodiment of the cannula accordingto the invention in a perspective view;

FIGS. 3 a to 3 b illustrate a third embodiment of the cannula accordingto the invention in transverse cross section.

FIG. 1 a represents a cannula 1 according to the invention arranged sothat it can be moved in a tubular sheath 2 of flexible plastic. Thecannula and the tubular sheath respectively present fittings 3, 4,connected to one another removably. The cannula 1 has an inner diameterto house a catheter—not represented in the Figures—which can be insertedinto the cannula so that it can move along the longitudinal direction.FIG. 1 a illustrates the cannula 1 as delivered. The length of thetubular sheath 2 is dimensioned so that the tip 1 a of the cannula 1 isretracted inside the tubular sheath 2 and does not represent any danger.

A catheter not represented in the figure can be inserted into thecannula from the end of the cannula on which the fittings 3, 4 arearranged. The catheter is first of all inserted until its end staysinside of the cannula 1.

It can be seen on figure 1 b that the fittings of the cannula 1 and ofthe tubular sheath 2 can be moved relative to one another so that thecannula 1 can be moved within the tubular sheath so that its tip 1 aprotrudes from the tubular sheath 2. The cannula 1 may thus be used forpuncturing a body cavity.

The fittings 3, 4 are designed in the represented embodiment so thatthey can be guided inside one another in the longitudinal direction. Thefitting 4 of the tubular sheath 2 therefore includes notches 5 (FIG. 1a) snapping into the hollows 6 on the fittings 4 of the cannula 1 whenthe latter is completely retracted into the tubular sheath 2 (FIG. 1).The snapping position excludes any possibility of unintentionallyextending the tip of the cannula 1 a outside the tubular sheath 2 andany risk of injury. For the cannula 1 to go from the delivery conditionaccording to FIG. 1 a to the puncture condition according to FIG. 1 b,the notches 5 must be depressed. The tubular sheath 2 can only then bemoved backwards.

If the body cavity is punctured with the cannula 1, the catheter can beinserted into the body cavity via the cannula 1. The cannula 1 can thenbe removed along with the tubular sheath 2. If the cannula 1 and thetubular sheath 2 are completely extracted from the patient's body, theyare still on the catheter. The cannula 1 then represents a significantrisk of injuries and should be removed. To this purpose, the cannula 1is extracted from the tubular sheath 2. The fittings 3, 4 are thereforeseparate from one another and the fitting 4 of the tubular sheath 2 ispushed in the direction of the tip of the cannula 1. The cannula 1 canthen be removed completely from the tubular sheath 2, as shown in FIG. 1c, The longitudinal slot 10 enables to remove the catheter from thecannula 1. It is not necessary to break the cannula 1 or to treat it inany other form.

The tubular sheath 2 is still situated on the catheter which is notrepresented in the figures. It is made of plastic and does not representany particular risk of injury. It may stay on the catheter or be removedtherefrom, e.g. by breaking it along a rupture line not represented.Contrary to the metal cannulas to be broken, protruding edgesrepresenting a significant risk of injuries do not risk forming on therims of the plastic tubular sheath.

FIGS. 2 a to 2 d represent a second embodiment of a cannula 1 accordingto the invention. FIGS. 2 a and 2 b essentially correspond to FIGS. 1 aand 1 b. FIG. 2 a illustrates a cannula 1 as delivered with a tubularsheath 2. To achieve the condition represented in FIG. 2 b, the fittings3, 4 are moved relative to one another here as well after snapping thenotches 5 so that the tip 1 a of the cannula 1 comes out of the tubularsheath 2 and that the cannula 1 may be used for the puncture.

As indicated in FIG. 2 c, the tubular sheath 2 of the embodiment ofFIGS. 2, contrary to the embodiment of FIGS. 1, is fitted with tworupture lines 7 as well as a manipulation section 9 connected to thewall section 8 between the rupture lines 7. If the cannula 1 iswithdrawn from the patient's body, the tubular sheath is first of allagain moved forward in the direction of the tip 1 a of the cannula untilthe notches 5 snap into the hollow sections 6. The tip 1 a of thecannula 1 is then brought back into the tubular sheath 2 and protected.

To remove the cannula from the catheter, the wall section 8 of thetubular sheath 2 between the rupture lines 7 is withdrawn using themanipulation section 9. To this purpose, the manipulation section 9 ispulled upwards as shown on FIG. 2 c.

It can be seen on FIG. 2 d that the withdrawal of the wall section 8between the rupture lines 7 clears the longitudinal slot 10 from thecannula 1. The cannula 1 can thus be removed from the catheter withoutproblems. Fitting the connection elements 3, 4 using notches enables toconnect the tubular sheath 2 and the cannula 1 to one another durably,even once the catheter has been withdrawn. The tip 1 a of the catheter 1is still protected in the remaining part of the tubular sheath and doesnot present any risk of injury.

FIGS. 3 a to 3 b illustrate a third embodiment of the cannula accordingto the invention in transverse cross section. As indicated in FIG. 3 a,the tubular sheath 2 is arranged in this embodiment inside the cannula1. Same as for the other embodiments, the sheath 2 can be moved in thelongitudinal direction in the cannula 1. In a first protection position,the sheath 2 protrudes from the tip of the cannula 1 and therebyexcludes the risk of needle jab on the tip. In a second punctureposition, the sheath 2 is withdrawn towards the inside of the cannula,and the puncture can be carried out.

The sheath 2 includes a catheter 11 which may be fed forward afterpuncture for insertion into the body cavity. The cannula 1 is thenwithdrawn. To be removed from the catheter 11, the sheath 2 exhibits tworupture lines 7 for removing the wall section 8 therebetween.

FIG. 3 b shows the assembly formed by the cannula 1, the tubular sheath2 and the catheter 11 after removing the wall section between therupture lines 7. The wall section removed from the sheath 2 correspondsto the slot 10 of the cannula. The cannula 1 and the sheath 2 can beremoved from the catheter 11 without any the risk of injury or damagingthe catheter 11.

1. A catheter with removable cannula (1) for puncturing a body cavity,whereas the catheter can be moved in the longitudinal direction in thecannula (1), characterised in that the cannula (1) is tubular in shapeand provided with a longitudinal slot (10), whereas said longitudinalslot (10) extends over 45° to 180° of the circumference of the cannula(1), and in that the cannula (1) and the catheter are arranged in atubular sheath (2) so that it can be displaced in the longitudinaldirection inside said tubular sheath (2).
 2. A catheter with removablecannula (1) for puncturing a body cavity, whereas the catheter can bemoved in the longitudinal direction in the cannula (1), characterised inthat the cannula (1) is tubular in shape and provided with alongitudinal slot (10), whereas said longitudinal slot (10) extends over45° to 180° of the circumference of the cannula (1), and in that atubular sheath is arranged inside the cannula so that it can bedisplaced in the longitudinal direction inside said cannula (2), whereasthe catheter is arranged inside the tubular sheath.
 3. A catheteraccording to claim 1, characterised in that the longitudinal slot (10)of the cannula (1) extends over 45 to 180 of the circumference of thecannula (1), in particular over
 150. 4. A catheter according to claim 1,characterised in that the tubular sheath (2) is made of plastic, inparticular made of flexible plastic.
 5. A catheter according to claim 1,characterised in that the tubular sheath (2) exhibits at least onerupture line (7). preferably two, in the longitudinal direction.
 6. Acatheter according to claim 5, characterised in that the tubular sheath(2) exhibits two rupture lines (7) and in that the wall section (8)between the rupture lines (7) is connected to a manipulation section (9)and be removed.
 7. A catheter according to claim 1, characterised inthat the cannula (1) and the tubular sheath (2) exhibit respectively afitting element (3, 4) enabling to connect them to one anotherremovably.
 8. A catheter according to claim 1, characterised in that thefitting elements (3, 4) of the cannula (1) and of the tubular sheath (2)are snapped to one another in a position in which the tip (1 a) of thecannula (1) is included in the tubular sheath (2).
 9. A cannula (1) forthe use with a catheter which can be moved in the cannula (1)characterised in that the cannula (1) is tubular in shape and providedwith a longitudinal slot (10), whereas said longitudinal slot (10)extends over 45° to 180° of the circumference of the cannula (1), and inthat the cannula (1) is arranged inside a tubular sheath (2) so that itcan be displaced in the longitudinal direction inside said sheath (2).10. A cannula (1) for the use with a catheter which can be moved in thecannula (1) characterised in that the cannula (1) is tubular in shapeand fitted with a longitudinal slot (10), whereas said longitudinal slot(10) extends over 45° to 180° of the circumference of the cannula (1),and in that a tubular sheath is arranged inside the cannula so that itcan be displaced in the longitudinal direction inside said cannula (2).11. A cannula (1) according to claim 9, characterised in that thelongitudinal slot (10) of the cannula (1) extends over 130° to 170° ofthe circumference of the cannula (1), in particular 150°.
 12. A cannula(1) according to claim 9, characterised in that the tubular sheath (2)is made of plastic, in particular made of flexible plastic.
 13. Acannula (1) according to claim 9, characterised in that the tubularsheath (2) exhibits at least one rupture line (7), preferably two, inthe longitudinal direction.
 14. 14. A cannula (1) according to claim 13,characterised in that the tubular sheath (2) exhibits two rupture lines(7) and in that the wall section (8) between the rupture lines (7) isconnected to a manipulation section (9) and can be removed.
 15. Acannula (1) according to claim 9, characterised in that the cannula (1)and the tubular sheath (2) exhibit respectively a fitting element (3, 4)enabling to connect them to one another removably.
 16. A cannula (1)according to claim 9, characterised in that the fitting elements (3, 4)of the cannula (1) and of the tubular sheath (2) are snapped to oneanother in a position in which the tip (1 a) of the cannula (1) isenclosed in the tubular sheath (2).
 17. A catheter according to claim 2,characterised in that the longitudinal slot (10) of the cannula (1)extends over 45 to 180 of the circumference of the cannula (1). inparticular over
 150. 18. A catheter according to claim 2, characterisedin that the tubular sheath (2) is made of plastic, in particular made offlexible plastic.
 19. A catheter according to claim 2, characterised inthat the tubular sheath (2) exhibits at least one rupture line (7),preferably two, in the longitudinal direction.
 20. A catheter accordingto claim 19, characterised in that the tubular sheath (2) exhibits tworupture lines (7) and in that the wall section (8) between the rupturelines (7) is connected to a manipulation section (9) and be removed. 21.A catheter according to claim 2, characterised in that the cannula (1)and the tubular sheath (2) exhibit respectively a fitting element (3, 4)enabling to connect them to one another removably.
 22. A catheteraccording to claim 2, characterised in that the fitting elements (3, 4)of the cannula (1) and of the tubular sheath (2) are snapped to oneanother in a position in which the tip (1 a) of the cannula (1) isincluded in the tubular sheath (2).
 23. A cannula (1) according to claim10, characterised in that the longitudinal slot (10) of the cannula (1)extends over 130° to 170° of the circumference of the cannula (1), inparticular 150°.
 24. A cannula (1) according to claim 10, characterisedin that the tubular sheath (2) is made of plastic, in particular made offlexible plastic.
 25. A cannula (1) according to claim 10, characterisedin that the tubular sheath (2) exhibits at least one rupture line (7),preferably two, in the longitudinal direction.
 26. A cannula (1)according to claim 25, characterised in that the tubular sheath (2)exhibits two rupture lines (7) and in that the wall section (8) betweenthe rupture lines (7) is connected to a manipulation section (9) and canbe removed.
 27. A cannula (1) according to claim 10, characterised inthat the cannula (1) and the tubular sheath (2) exhibit respectively afitting element (3, 4) enabling to connect them to one anotherremovably.
 28. A cannula (1) according to claim 10, characterised inthat the fitting elements (3, 4) of the cannula (1) and of the tubularsheath (2) are snapped to one another in a position in which the tip (1a) of the cannula (1) is enclosed in the tubular sheath (2).